Many schemes currently exist in battery powered equipment for the equipment to provide an indication of a battery level to a user during operations. Such schemes include simple measuring of battery terminal voltage. Such arrangements are not very satisfactory because a typical rechargeable battery, e.g. a nickel-cadmium battery, does not exhibit very great voltage changes over a wide range of charging levels.
Better schemes use a current integration technique to integrate currently flowing from and to the battery and to count up and count down a charge value indicative of charge remaining on the battery. A problem with current integration is keeping track of remaining battery capacity, such that inaccuracies in the integration can accumulate in counting up, and counting down, so as to lead to large errors over time. Also it is a problem that a low battery indication can be given too soon or too late.
There is a need for an improved battery gauge and method for gauging battery charge.
A preferred embodiment of the present invention is now described, by way of example only, with reference to the drawings.